Extra dimensions and strong neutrino nucleon interactions above 10**19-eV: Breaking the GZK barrier

Jan, 2000
15 pages
Published in:
  • Phys.Lett.B 484 (2000) 267-274
e-Print:

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Abstract:
Cosmic ray events above 102010^{20} eV are on the verge of confronting fundamental particle physics. The neutrino is the only candidate primary among established particles capable of crossing 100 Mpc intergalactic distances unimpeded. The magnitude of νN\nu N cross sections indicated by events, plus consistency with the Standard Model at low-energy, point to new physics of massive spin-2 exchange. In models based on extra dimensions, we find that the νN\nu N cross section rises to typical hadronic values of between 1 and 100 mb at energies above 102010^{20} eV. Our calculations take into account constraints of unitarity. We conclude that air-showers observed with energies above 101910^{19} eV are consistent with neutrino primaries and extra-dimension models. An {\it upper bound} of 1-10 TeV on the mass scale at which graviton exchange becomes strong in current Kaluza-Klein models follows.
  • neutrino: cosmic radiation
  • cosmic radiation: primary
  • neutrino nucleon: interaction
  • total cross section: energy dependence
  • showers: air
  • model: higher-dimensional
  • graviton: exchange
  • Kaluza-Klein model
  • electroweak interaction
  • unitarity